var code;
	function createCode() {
		code = "";
		var codeLength = 6; //验证码的长度
		var checkCode = document.getElementById("checkCode");
		var codeChars = new Array(0, 2, 3, 4, 5, 6, 7, 8, 9, 'a', 'b', 'c',
				'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm', 'n',
				'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A',
				'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
				'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'); //所有候选组成验证码的字符，当然也可以用中文的
		for (var i = 0; i < codeLength; i++) {
			var charNum = Math.floor(Math.random() * 52);
			code += codeChars[charNum];
		}
		if (checkCode) {
			checkCode.className = "code";
			checkCode.innerHTML = code;
		}
	}
	function validateCode() {
		var inputCode = document.getElementById("inputCode").value;
		if (inputCode.length <= 0) {
			document.getElementById("sure").innerText = "请输入验证码！"
			document.getElementById("sure").style.color = "red"
				return false;

		} else if (inputCode.toUpperCase() != code.toUpperCase()) {
			document.getElementById("sure").innerText = "验证码输入有误！"
			document.getElementById("sure").style.color = "red"
			createCode();
			return false;
		} else {
			document.getElementById("sure").innerText = "验证码正确！"
			document.getElementById("sure").style.color = "green"
				return true;
		}
	}
	/*<html>
<head>
<meta charset="utf-8" />
<title>js验证码</title>
<style type="text/css">
.code 
{
 background:url(code_bg.jpg);
 font-family:Arial;
 font-style:italic;
 color:blue;
 font-size:30px;
 border:0;
 padding:2px 3px;
 letter-spacing:3px;
 font-weight:bolder;
 float:left;
 cursor:pointer;
 width:150px;
 height:60px;
 line-height:60px;
 text-align:center;
 vertical-align:middle;
}
a 
{
 text-decoration:none;
 font-size:12px;
 color:#288bc4;
}
a:hover 
{
 text-decoration:underline;
}
</style>
<script type="text/javascript" src="http://git.oschina.net/oceanao/js/raw/6ece210da8896af1eb9fde25f7866835157d22f0/sure_picture.js">
</script>
</head>
<body onload="createCode()">
<form  id="form1" runat="server">
 <div>
  <table border="0" cellspacing="5" cellpadding="5" >
   <tr>
    <td></td>
    <td><div class="code" id="checkCode" onclick="createCode()" ></div></td>
    <td><a href="#" onclick="createCode()">看不清换一张</a></td>
   </tr>
   <tr>
    <td>验证码：</td>
    <td><input style="float:left;" type="text"  id="inputCode"  onblur="validateCode()"/></td>
    <td><span id="sure">请输入验证码</span></td>
   </tr>
   <tr>
    <td></td>
    <td><input id="Button1" onclick="validateCode();" type="button" value="确定" /></td>
    <td></td>
   </tr>
  </table>
 </div>
</form>
</body>
</html>*/